A growing body of literature illustrates that once a smoker has been diagnosed with cancer, immediate smoking cessation is medically warranted because continued smoking contributes to several adverse health outcomes for cancer patients (e.g., reduction in treatment efficacy, increased risk of developing a second primary cancer, poorer survival). Given the large number of cancer patients making a quit attempt and the high rate of smoking relapse, there is a critical need for evidence-based smoking relapse-prevention interventions for this population. To our knowledge, no smoking relapse-prevention interventions exist for cancer patients. Therefore, the primary aim of this study is to address this gap by testing the efficacy of an empirically based, targeted smoking relapse-prevention intervention for cancer patients. We propose a multimodal intervention comprised of a targeted digital videodisc (DVD) designed specifically for cancer patients and accompanying relapse prevention booklets (Forever Free) that have been previously demonstrated efficacious with the general smoking population. The key content of the targeted DVD is based on Witkiewitz and Marlatt's cognitive-behavioral model of relapse, existing literature, and our prior qualitative and quantitative smoking relapse research conducted with cancer patients. Examples of targeted content include: the effects of continued tobacco use on cancer treatment; benefits of quitting for cancer patients; and interviews with cancer patients who have been successful at maintaining their smoking abstinence. Participants (N = 414) will be randomized to receive usual care (UC) or usual care plus our Smoking Relapse Prevention for Cancer Patients (SRP-CaP) intervention. Based on previous research, we hypothesize that cancer patients who receive the SRP-CaP intervention will demonstrate lower rates of smoking relapse at 6 and 12-month follow-up, relative to patients in the UC condition. Secondary aims of this study are to evaluate the impact of potential mediating and moderating variables on intervention outcomes. The inclusion of possible moderators will allow us to examine whether future relapse-prevention interventions with cancer patients should include additional tailoring. The identification of mediators of intervention effects will guide the development of future smoking interventions as well as aid in the conceptualization of a smoking relapse framework for cancer patients. If demonstrated effective, the proposed intervention would represent an easily disseminable and low-cost intervention with significant public health implications, including improved physical functioning, quality of life, and survival for cancer patients.